Hello friends, I first thought about reporting this issue properly to the bug thread, but then decided it doesn't really look like ufoconlose.log and savegames would be of help in identifying its cause. The thing is, the moon seems to eclipse the sun in a rather weird way on the geoscape.
I don't know much about how the lighting is rendered, but perhaps it would be more accurate if the moon was just allowed to block the inner circle as well as the corona without any actual change in lighting, or with a slight dimming of the entire geoscape